1. Technical Field
The present invention relates to tool-path data generation apparatuses that automatically generate tool-path data, including transfer pathway and cutting parameters, for cutting tools in numerical-control machining centers (“NC machine tools”), and also relates to numerical controllers provided with such tool path data generation apparatuses.
2. Description of the Related Art
As an apparatus for automatically generating tool path data by using design data of an object to be cut (hereinafter referred to as a workpiece) being created by CAD (Computer Aided Design), a tool path data generation apparatus using a CAM (Computer Aided Manufacturing) method has been widely known.
Design data created by CAD (hereinafter referred to as CAD data) comprises geometry data—for example, coordinate data, formula data, and data on dimension lines—indicating final form and dimensions of the workpiece after being cut. The tool path data generation apparatus extracts only workpiece geometry data from such CAD data, thereafter timely receives data necessary to generate tool path such as data on features of the workpiece form—as to whether the features will be circular, rectangular, round-columnar, square-columnar, protruding contours, or recessed contours—and also data on cutting methods such as type of tool and cutting conditions, through input by an operator operating an input unit, and finally generates tool path data on the basis of such input data and geometry data extracted from the CAD data.
However, in the above-described ordinary tool-path data generation apparatus, since data on the features of the workpiece shape as well as data on the cutting methods—both of which are necessary to generate tool path data—must be inputted by the operator, the data input process is time-consuming, such that machining of the workpiece is itself time-consuming. In addition, it is very difficult to completely prevent human-caused input errors, owing to which problems such as the workpiece turning out defective or the workpiece jig and cutting tool being damaged can occur. Such problems may cause other, critical problems in one-off (custom) manufacture, for example, the production of a mold.
If an expected result cannot be obtained because of tool chatter and overload caused by cutting when an NC cutting program is created on the basis of tool path data generated by the tool path data generation apparatus, to carry out machining by the NC machine tool using the above-mentioned NC cutting program, it is necessary to correct the NC cutting program after investigating the causes, which can be time-consuming, further it is also necessary to trace back to an initial cutting stage in the tool path data generation apparatus for executing the above-mentioned correction. As a result it takes another long period to re-output the NC cutting program, such that the machine tool has to be stopped during such period, consequently productivity is deteriorated.
In view of the foregoing, it is an object of the invention to provide a tool path data generation apparatus which can speedily and securely generate and correct tool path data on the basis of CAD data, and also to provide a numerical controller provided with such a tool path data generation apparatus.